The present invention relates to microporous films and, more particularly, relates to patterned embossed multilayered films and methods of making the same.
Absorbent articles, for example personal care products, generally comprise an absorbent material for absorbing and retaining liquids and a liquid impervious outer cover. Various films have been used heretofore within the outer cover to provide a liquid barrier and prevent leakage of liquids from the absorbent material. These films have employed various pigments or opacifying fillers in order to provide an opaque film that masks the interior of the article. Examples of such opaque films are described in U.S. Pat. No. 5,006,394 to Baird and U.S. Pat. No. 5,261,899 to Visscher et al. In addition, outer covers for personal care articles have also utilized embossed multilayer structures to provide a film having multi-colored patterns therein. As an example, U.S. Pat. No. 5,897,541 to Uitenbroek et al. describes a multilayer structure comprising a first layer having opaque areas and transparent areas and a second layer of a colored material wherein the color of the second layer shows through the transparent areas of the first layer. In one embodiment, the first layer can comprise an opaque microporous film having transparent areas, formed therein by the application of heat and/or pressure, wherein the color of an underlying layer shows through the parent areas, In addition, UK Patent No. 1,070,514 teaches a white, substantially opaque polybutylene film which can be rendered substantially transparent in areas subjected to heat or pressure. Color can show through the transparent areas when the polybutylene film is laminated to a colored substrate. In a similar aspect, U.S. Pat. No. 4,623,340 to Luceri teaches a body-side layer for an absorbent product comprising an outer light colored liquid-pervious, opaque sheet, such as a nonwoven web or perforated film, and an inner dark colored sheet. The two layers are co-embossed to form depressed areas and undepressed areas wherein the depressed areas color contrast with the light- colored undepressed areas.
However, highly breathable microporous films are often extremely thin films that provide reduced opacity characteristics. Thus, the ability to provide the desired color contrast through embossed multilayer structures is diminished since the color of an underlying dark layer will show through thin microporous film resulting in limited or poor color contrast. Further, the ability of such films to adequately mask and/or neutralize colors within the interior of personal care articles has also proven difficult to achieve.
The aforesaid needs are fulfilled and the problems experienced by those skilled in the art overcome by multilayer films of the present invention comprising: (i) a first microporous layer having a thickness less than about 30 micrometers and comprising polymer and at least 35%, by weight, filler; and (ii) a second microporous layer substantially continuously joined to the first layer and having a thickness less than about 30 micrometers, the second microporous layer comprising polymer, coloring agent and at least 35%, by weight, filler. The multilayer films have a total basis weight less than about 45 g/m2, a WVTR in excess of 500 g/m2/24 hours and a hydrohead of at least 50 mbars. Additionally, the multilayer films have embossed and non-embossed regions wherein the embossed regions color-contrast with said non-embossed regions. Desirably, the second layer is darker than the first layer and the embossed regions of the first layer are translucent. The embossed regions of the second layer can be translucent or opaque. In a further aspect, the second layer can comprise a multi-toned film wherein the color within the embossed regions is darker than that within the non-embossed regions and/or has a more intense color than that within the non-embossed regions. Further, the non-embossed regions of the second layer desirably have a Hunter Color Number L* above 70. The multilayer film can further comprise addition microporous layers as desired. The multilayer films of the present invention can also be used to form multilayer laminates such as, for example, nonwoven/film laminates. The multilayer films and laminates thereof have numerous applications and are particularly well suited for use as or within a liquid impervious outer cover for personal care articles.